__flush_hash_table_range(9)

🌸 __flush_hash_table_range — NAME ✨

ok so __flush_hash_table_range 💅 — it flushes all the HPTEs for a given address range out of the hash table (and the TLB too, bestie!), but lowkey leaves the linux PTEs completely intact. no cap, they stay right where they are 🫶

(this is page 9 of the Kernel API Manual, mwah 💖)

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🦋 SYNOPSIS

void __flush_hash_table_range (unsigned long start , unsigned long end );

like, that's the whole signature. two unsigned longs and vibes ✨

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🎀 ARGUMENTS

• start — the starting address. where the party begins 🎉
• end — the ending address, and heads up: it's not included in the flush 🙈 (exclusive, iykyk)

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👑 DESCRIPTION

ok so picture this: this function is mostly meant to be used by some IO hotplug code 🔥 the goal is to remove all the hash entries from a given address range that was used to map IO space on a removed PCI-PCI bridge — without tearing down the full mapping. why? because 64K pages may overlap with other bridges when you're using 64K pages with 4K HW pages on IO space 😭 it's giving "surgical, not scorched-earth."

and because of that exact usage pattern, it's implemented for small size rather than speed 💀 so don't come at it expecting a speed demon — it was built petite, not fast. periodt.

ngl, it's a small-and-mighty situation, not a benchmark queen 👑

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🌈 SEE ALSO

• Kernel file ./arch/powerpc/mm/book3s64/hash_tlb.c — go read it bestie, it's right there 🧚

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⭐💜 that's the whole page, fr fr. brought to you by ./arch/powerpc/mm/book3s64, dated October 2026, and honestly? iconic. slay 💅✨🎀